A signal lamp, especially for motor vehicles, contains multiple lighting units wherein each of these lighting units provides a different light function or contributes to ensuring the required emission characteristic of the light trace. Individual lighting units are generally mounted in a shaped carrying housing of the lamp, while each unit contains at least one light source and other optical elements. The light source emits light rays and the optical elements represent a system of refractive and reflective surfaces and interfaces of optical environments that influence the direction of light rays within the creation of the output light trace.
In modern headlights of motor vehicles, lighting units containing light sources in the form of semiconductor elements are frequently used. Advantages of LED light sources include durability, compact dimensions, low power consumption and higher designer variability of the optical concept. A disadvantage of optical concepts equipped with LED light sources is the fact that to provide the required output characteristics of the light trace and to create spatial light effects or other design elements, a higher number of LED's must be used.
A laser diode is known from the prior art, at the PN junction of which electric power is transformed to light. Unlike LED's, light corresponding with its characteristics to laser light is generated. The emitted light has a significantly narrower spectrum, it is strongly monochromatic and is coherent.
Thus, laser diodes may be used, unlike LED's, in applications where a sharply directional light beam is required. The documents US20110280032A1, WO2015140001A1, US20150043233A1, WO2014121315A1 have disclosed light devices where laser diodes make it possible to precisely focus light rays in a particular direction and also to hit a very distant point, which is used in the headlights of motor vehicles to ensure the high beam function wherein the light may be emitted up to the distance of 600 m in front of the vehicle because, thanks to the better targetability of the laser diode, the laser beam does not lose more than 20% of its light, while in the case of LED's up to 80% of light rays may be lost or scattered this way. Another advantage of laser diodes is the fact that optical concepts using laser diodes may be up to 1000 times more powerful than LED's, only consuming two thirds of energy compared to them. A disadvantage of laser as well as LED optical concepts is the fact that excessive light intensity may harm vision and the headlights of vehicles must be fitted with safety elements to avoid exceeding of safety limits, especially in case of damage of fluorescent phosphor substances or the entire laser diodes. Safety elements for laser beam emission are described e.g. in the documents WO2014072227A1, EP2821692A1, WO2015049048A1, WO2012076296A3, U.S. Pat. No. 8,502,695B2. A disadvantage of present optical concepts is the fact that the benefits of laser diodes are mainly used for the headlights of motor vehicles where a high-intensity light trace must be provided, while blue and white light may harm vision.
From the prior art, diffraction dividers of the laser beam are known that consist of a binary grating that is designed in such a way to divide coherent light emitted from the laser diode to a particular number of light streams. The surface microstructure of the binary grating acts as a photon router to direct photons to a pre-defined space, while the shape of the binary grating determines the shape and number of individual light streams and the shape and position of the output light patterns on the display surface. The topographical profile of the diffraction grating may have more surface levels that are made of etched silica glass and/or another glass type and/or polymeric material. A disadvantage of the prior art is the fact that optical systems comprising a laser beam diffraction divider are not adapted to create the required output characteristics for lighting devices intended for land road traffic.
The documents U.S. Pat. Nos. 6,529,678, 8,465,193, 6,529,678 disclose designs of optical means for propagation of light in such a way that at the output the light propagates at a certain defined space angle and with a defined intensity distribution. The document US20140307457 discloses a lamp equipped with a light source designed to emit a laser beam as well as with a light dividing element arranged in the emission direction of the light beam from the laser source to divide the laser beam into a higher number of partial beams. Elements for routing the partial beams to a plane parallel to the original laser beam are arranged in the direction of the partial beams, while the partial beams are bound to light diffusion elements in the form of lenses to achieve a homogeneous distribution of light. The diffused light is directed onto a screen fitted with a microstructural surface that contributes to homogeneous diffusion of light generated by the laser source, wherein a lit band or area is emitted onto the display surface to fulfil the daytime lighting function. A disadvantage of this design consists in limited designer possibilities because they do not make it possible to create a light trace of an irregular shape or to meet designer requirements for the output light beam when a spatial or design effect is required to be produced in the front view. The prior-art solution is not designed to provide more various lighting functions.
The goal of the invention is to design a light device, especially a signal lamp for motor vehicles that makes it possible to create spatial light effects or to meet other design requirements for the output light beam and at the same time is adapted to ensure several light functions of a lamp, while to provide the required output characteristics of the light trace and to create spatial light effects or other design elements a relatively small number of light sources, especially in the form of a laser diode, need to be used.